Method and apparatus for positioning a workpiece and tooling

Abstract

A method and apparatus for positioning the top surface of a workpiece in proper relationship with respect to tooling including a fully extended upper clamp bushing, or for positioning the fully extended upper clamp bushing in proper relationship with respect to the top surface of a workpiece, which establishes a desired workplane wherein the top surface of the workpiece is always disposed in a normal position with respect to the lowermost surface of the upper clamp bushing and just in contact with the lowermost surface even though the top surface was disposed either below or above the desired workplane at the commencement of the clamping operation. The method and apparatus is capable of moving the top surface of the workpiece or the tooling into a desired workplane and also of determining whether or not the top surface of the workpiece adjacent the area which is to be fastened lies within the desired workplane. The apparatus including a plurality of position sensors associated with the upper clamp bushing, which sensors are capable of sensing when the upper clamp bushing contacts the top surface of the workpiece or is contacted by it, the apparatus further including a control for moving the workpiece to the desired position in response to the position sensors.

What is claimed is: 
     
       1. A method of providing a proper positional relationship between a workpiece assembly and tooling carried by a movable frame, said workpiece assembly having a top surface and said assembly comprising two or more workpieces one of which is atop workpiece having an upper surface, which tooling is used to initially clamp together the two or more workpieces and to then fasten the workpieces together, the tooling including an upper clamp bushing having a lower surface and carried by an upper pressure foot plate, the lower surface of the upper clamp bushing establishing a desired workplane when the upper pressure foot plate is fully lowered and the upper bushing is in proper engagement with the upper surface of the top workpiece; the method comprising the following steps: providing a workpiece holding apparatus;   providing a movable frame and tooling mounted on the frame, the tooling being movable in a horizontal plane and including an upper pressure foot plate movable from a raised retracted position to fully lowered position, and an upper clamp bushing carried by the upper pressure foot plate for limited vertical shifting movement with respect to the upper pressure foot plate, the upper clamp bushing having a lower planar workpiece engaging surface;   moving the tooling in a horizontal plane with the upper pressure foot plate in its raised retracted position to an operational position where the upper clamp bushing is substantially in line with a location where a fastener is to be inserted;   moving the upper pressure foot plate downwardly towards its fully lowered position; and a) either sensing when the upper pressure foot plate has attained its fully lowered position, and then, causing relative movement between the workpiece assembly and the tooling in such a manner that the top surface of the workpiece is in flush clamping contact with the lower surface of the upper clamp bushing if the top surface of the workpiece assembly is not in flush clamping contact with the lower surface of the upper clamp bushing; or   b) sensing when the lower surface of the upper clamp bushing is in force applying contact with the top surface of the workpiece assembly, and then causing relative movement between the workpiece assembly and the tooling in such a manner that the top surface of the workpiece is in flush contact with the lower surface of the upper clamp bushing and then causing relative movement between the upper pressure foot plate and the workpiece assembly until the upper pressure foot plate has achieved its fully lowered position.     
     
     
       2. The method of claim 1, wherein the workpiece holding apparatus is capable of moving the workpiece assembly up and down and wherein said steps of causing relative movement between the workpiece assembly and the tooling in such manner that the top surface of the workpiece is in flush clamping contact with the lower surface of the upper clamp bushing comprise moving the workpiece upwardly when the pressure foot plate has attained its fully lowered position. 
     
     
       3. The method of claim 1, wherein the workpiece holding apparatus is capable of moving the workpiece assembly up and down and wherein said step of causing relative movement between the upper pressure foot plate and the workpiece assembly comprises moving the workpiece downwardly unitl the pressure foot plate has achieved its fully lowered position. 
     
     
       4. The method of claim 1, further including sensing whether or not the top surface of the workpiece assembly is in flush clamping contact with the lower surface of the upper clamp bushing. 
     
     
       5. The method of claim 1, wherein the workpiece holding apparatus is capable of moving the ends of the workpiece assembly independently up and down and is further capable of rotating the workpiece assembly about a line which extends between the ends of the workpiece assembly, and wherein said steps of causing relative movement between the workpiece assembly and the tooling in such a manner that the top surface of the workpiece assembly is in flush clamping contact with the lower surface of the upper clamp brushing comprise moving the ends of the workpiece assembly independently up and down or rotating the workpiece assembly about the line which extends between the ends of the workpiece assembly. 
     
     
       6. The method of claim 5, further including sensing whether or not the top surface of the workpiece assembly is in flush clamping contact with the lower surface of the upper clamp bushing. 
     
     
       7. The method of claim 1, wherein the frame includes means for moving the tooling toward and away from the workpiece and wherein said steps of causing relative movement between the workpiece assembly and the tooling in such manner that the top surface of the workpiece is in flush clamping contact with the lower surface of the upper clamp bushing comprise moving the tooling downwardly when the pressure foot plate has attained its fully lowered position. 
     
     
       8. The method of claim 1, wherein the frame includes means for moving the tooling toward and away from the workpiece and wherein said step of causing relative movement between the workpiece and the tooling comprises moving the tooling upwardly until the pressure foot plate has achieved its fully lowered position. 
     
     
       9. The method of claim 1, wherein the frame includes means for rotating the tooling about roll and pitch axes and wherein said steps of causing relative movement between the workpiece assembly and the tooling in such a manner that the top surface of the workpiece assembly is in flush clamping contact with the lower surface of the upper clamp bushing comprise moving the tooling about the roll or the pitch axes. 
     
     
       10. The method of claim 9, further including sensing whether or not the top surface of the workpiece assembly is in flush clamping contact with the lower surface of the upper clamp bushing. 
     
     
       11. Apparatus for providing a proper positional relationship between a workpiece assembly and tooling carried by a movable frame, said workpiece assembly having a top surface and said assembly comprising two or more workpieces one of which is a top workpiece having an upper surface, which tooling is used to initially clamp together the two or more workpieces and to then fasten the workpieces together, the tooling including an upper clamp bushing having a lower surface and carried by an upper pressure foot plate, the lower surface of the upper clamp bushing establishing a desired workplane when the upper pressure foot is fully lowered and the upper bushing is in proper engagement with the upper surface of the top workpiece; the apparatus comprising the following: workpiece holding means;   a movable frame;   tooling mounted on the frame, the tooling being movable in a horizontal plane, the tooling including an upper pressure plate movable from a raised retracted position to a fully lowered position, and   an upper clamp bushing carried by the upper pressure foot plate for limited vertical shifting movement, the upper clamp bushing have a lower planar workpiece engaging surface;   means for moving the tooling in a horizontal plane with the upper pressure foot plate in its raised retracted position to the next operational position where the upper clamp bushing is substantially in line with location where a fastener is to be inserted;   means for moving the upper pressure foot place downwardly towards its fully lowered position;   first sensing means for sensing when the upper pressure foot plate has attained it fully lowered position;   second sensing means for sensing when the lower surface of the upper clamp bushing is in force applying contact with the top surface of the workpiece assembly; and   means for either causing relative movement between the workpiece assembly and the tooling in such manner that the top surface of the workpiece is in flush contact with the lower surface of the upper clamp bushing if the first sensing means initially senses attainment of the fully lowered position of the upper pressure foot plate or causing relative movement between the workpiece assembly and the upper pressure foot plate until the upper pressure foot plate achieves its fully lowered position if the second sensing means initially senses attainment of force applying contact by the upper clamp bushing.   
     
     
       12. Apparatus according to claim 11, wherein the workpiece holding means includes means for moving the workpiece assembly up and down and wherein the means for causing relative movement between the workpiece assembly and the tooling moves the workpiece assembly upwardly when the first sensing means initially senses attainment of the fully lowered portion of the upper pressure foot plate. 
     
     
       13. Apparatus according to claim 11, wherein the workpiece holding means includes means for moving the workpiece assembly up and down and wherein the means for causing relative movement between the upper pressure foot plate and the workpiece assembly moves the workpiece downwardly until the upper pressure foot plate achieves its fully lowered position. 
     
     
       14. Apparatus according to claim 13, wherein the means for causing relative movement between the workpiece assembly and the upper pressure foot plate comprises means for causing the workpiece holding means and the means for moving the upper pressure downwardly to move both the upper pressure foot plate and the workpiece assembly downwardly. 
     
     
       15. Apparatus according to claim 11, wherein the frame includes means for moving the tooling toward and away from the workpiece assembly and wherein the means for causing relative movement between the workpiece assembly and the tooling comprises means for moving the tooling downwardly when the first sensing means initially senses attainment of the fully lowered position of the upper pressure foot plate. 
     
     
       16. Apparatus according to claim 11, wherein the frame includes means for moving the tooling toward and away from the workpiece assembly and wherein the means for causing relative movement between the workpiece and the upper pressure foot plate includes means for moving the tooling and with it the upper pressure foot plate upwardly until the pressure foot achieves its fully lowered position. 
     
     
       17. Apparatus according to claim 11, wherein the second sensing means includes means for sensing whether or not the top surface of the workpiece assembly is in flush clamping contact with the lower surface of the upper clamp bushing. 
     
     
       18. Apparatus according to claim 17, wherein the workpiece holding means includes means for moving the ends of the workpiece assembly independently up and down and means for rotating the workpiece assembly about a line which extends between the ends of the workpiece assembly and wherein the means for causing relative movement between the workpiece assembly and the tooling causes the top surface of the workpiece assembly to be in flush clamping contact with the lower surface of the upper clamp bushing by moving the ends of the workpiece assembly independently up or down or by rotating the workpiece assembly about the line which extends between the ends of the workpiece assembly. 
     
     
       19. Apparatus according to claim 17, wherein the frame includes means for rotating the tooling about roll and pitch axes and wherein the means for causing relative movement between the workpiece assembly and the tooling causes the top surface of the workpiece assembly to be in flush clamping contact with the lower surface of the upper clamp bushing by moving the tooling about the roll or the pitch axes. 
     
     
       20. Apparatus according to claim 11 wherein the first sensing means includes a position encoder extending between the upper pressure foot plate and the frame. 
     
     
       21. Apparatus according to 11 wherein the second sensing means includes a plurality of individual sensors extending between the upper clamp bushing and the upper pressure foot plate. 
     
     
       22. A method for positioning a workpiece having a top surface in proper relationship with respect to tooling including a fully extended upper clamp bushing having a lowermost surface, or for positioning the fully extended upper clamp bushing in proper relationship with respect to the workpiece, which establishes a desired workplane wherein the top surface of the workpiece is always disposed in a normal position with respect to the lowermost surface of the upper clamp bushing and just in contact with the lowermost surface even though the top surface of the workpiece was disposed either below or above the desired workplane at the commencement of the clamping operation, said method comprising moving the top surface of the workpiece or the tooling into a desired workplane; determining whether or not the top surface of the workpiece adjacent an area which is to be fastened lies within the desired workplane by utilizing a plurality of position sensors associated with the upper clamp bushing which sensors are capable of sensing when the upper clamp bushing contacts the top surface of the workpiece or is contacted by it; and moving the workpiece in a controlled manner to the desired position in response to the determination provided by the position sensors. 
     
     
       23. Apparatus for positioning a workpiece having a top surface in proper relationship with respect to tooling including a fully extended upper clamp bushing having a lowermost surface, or for positioning the fully extended upper clamp bushing in proper relationship with respect to the workpiece, which establishes a desired workplane wherein the top surface of the workpiece is always disposed in a normal position with respect to the lowermost surface of the upper clamp bushing and just in contact with the lowermost surface even though the top surface of the workpiece was disposed either below or above the desired workplane at the commencement of the clamping operation, said apparatus comprising means for moving the top surface of a workpiece or the tooling into a desired workplane; means for determining whether or not the top surface of the workpiece adjacent an area which is to be fastened lies within the desired workplace including a plurality of position sensors associated with the upper clamp bushing, which sensors are capable of sensing when the upper clamp bushing contacts the top surface of the workpiece or is contacted by it; and   means for moving the workpiece in a controlled manner to the desired position in response to the determination provided by the position sensors.